canon rumors FORUM

Tijn

The poor quality images I produced are probably in large part due to errors in the raw conversion. When looking at the raw file in IrfanView zoomed in, it seems to display it in clusters of 8x8 pixels that seem to get some of the colours right, but these clusters have contrasty edges opposite to one another (making them visible).

It took me a few minutes to do the raw conversion, and I had problems with a magenta cast to images, so hopefully I can save the rest of you a bit of time.

I am attaching 100% crops as PNG files. I used shotwell (under linux) to convert to a tiff, then LR3.6 to crop and export as a jpeg (I tried to post a .png unsuccessfully earlier). As mentioned previously, it is possible that a better raw conversion would result in better quality; however, I have a 5d iii on pre-order and am trying to be realistic and restrain myself from wishful thinking.

Does anyone have a similar 5d ii shot to compare to? I would be very interested in seeing a side-by-side with a 5d ii shot at ISO 6400 and 3200 (but I only have a 5d classic).

Tijn

It took me a few minutes to do the raw conversion, and I had problems with a magenta cast to images, so hopefully I can save the rest of you a bit of time.

I got a similar "view" of the files using IrfanView. I am lead to believe that it is a faulty RAW conversion and that useful claims about noise cannot be made.Look at a 600% enlargement of the left top corner of the ISO 6400 image to see what I mean. 8x8 pixel "blocks" with articulated edges are visible that introduce incorrect "detail" that will mess with any kind of noise-reduction one might want to perform on it. I can only assume that that is a RAW conversion error.

erfon

you guys, the raw converter you use makes a BIG difference. raw photos are just RAW data, hence the name. the raw converter must use that data to construct an actual image.

you aren't really going to be able to tell much till canon or adobe give us a way to properly convert the mark iii raw files. converting mark iii files in other hacked ways like irfanview is interesting i admit, but it's not going to give you an accurate portrayal of how the mark iii really performs in low light.

i'm as eager as anyone to see how this baby does, but we gotta wait for a proper raw converter before we can really tell.

Does anyone have a similar 5d ii shot to compare to? I would be very interested in seeing a side-by-side with a 5d ii shot at ISO 6400 and 3200 (but I only have a 5d classic).

Well this is so Apples to Oranges as to be pointless but I took your 100% crop from the 5D3 ISO6400 and then downsampled it to an equivalent 100% crop from an 8MP camera (to match the only ISO6400 5D2 sample I can find for posting which was downsampled to 8MP).

It took me a few minutes to do the raw conversion, and I had problems with a magenta cast to images, so hopefully I can save the rest of you a bit of time.

I got a similar "view" of the files using IrfanView. I am lead to believe that it is a faulty RAW conversion and that useful claims about noise cannot be made.Look at a 600% enlargement of the left top corner of the ISO 6400 image to see what I mean. 8x8 pixel "blocks" with articulated edges are visible that introduce incorrect "detail" that will mess with any kind of noise-reduction one might want to perform on it. I can only assume that that is a RAW conversion error.

Are you sure irfanview is not just showing the highly compressed embedded jpg within the RAW file? JPG also compresses in 8x8 blocks I believe (although it shouldn't show itself as what you see so something is probably going wrong).

Logged

Tijn

Are you sure irfanview is not just showing the highly compressed embedded jpg within the RAW file? JPG also compresses in 8x8 blocks I believe (although it shouldn't show itself as what you see so something is probably going wrong).

I'm not sure of anything that Irfanview shows me. It may very well be what you said. All I know is it opens the RAW files and when zoomed out, they look like regular images. When zooming in very far is when I see those 8x8 blocks. And I see them in the RAW image opened in my own IrfanView, as well as in the PNG's posted by qwerty (who got them using "shotwell"). I think we're seeing the same image, and that it is either a crap/wrong conversion or something like you said (seeing the crap compressed JPG-within-the-RAW).

When a raw converter doesn't have a supplied profile, what does it do, just assume a standard bayer pattern of RGB and size it for the frame?

Each Raw image file also contains a jpeg file that is used for a thumbnail. It will show that jpeg thumbnail if it can't convert. The jpeg thumbnail is most likely what you are seeing. Some raw converters will try, and you get really weird images.

Just view out of camera jpegs like those on DPR. They are very carefully exposed, and are about the best high ISO images at full size we have.

I too was particularly impressed with the 6400 sample. The 51200... it is what it is. Sadly, some of my 12800 shots were underexposed due to being in M mode with Auto ISO capped at 12800 (Max auto ISO is selectable up to 25600 ftr). But I have at least one usable file that I will put in the OP later today.

canon rumors FORUM

I played around a bit with the codec available at http://wildtramper.com/sw/cr2/cr2.html, which allows you to specify whether you want to extract the embedded jpeg or the actual raw file. It looks like what I posted earlier was the embedded jpeg (thanks for pointing that out).

Color correction is not applied to the raw file by the extractor, so the colors are obviously off. The resulting size of the raw file was also about 5.8 MPix (1/4 the sensor resolution), so I assume that it does not do any sophisticated demosaicing. The jpeg was 22.1 MPix.

If someone has a 5d ii raw file with a similar composition, lighting, and iso, we should be able to get an apples-to-apples comparison here to see how the new sensor performs; just follow the same steps I did and post what you get. Obviously without the correct color profiles, the pictures will not look correct but, if the extractor does the same thing to files for both cameras, we can still make a comparison. Obviously there is the risk that the actual cr2 file format changed somehow between camera revisions, but I think its worth a shot.

I extracted both the jpeg and the raw file (as a tiff) using the program linked to above, then cropped using GIMP. I am going to try posting as a lossless .png first but, if I have problems with that, I will post as a jpeg saved at 100% quality.

Note: the image from the raw file is first, the embedded jpeg is second.

If I had a few more minutes with the camera, I would have shot some side by side comparisons with my trusty ol' 5DII. Anyway, I added a 12800 sample to the ISO. I would say it's comparable to 3200 on the Mark II.